Steel Survivor: an IBM XT Tale

This month actually marks the IBM 5160's 35th birthday, so why not show
off my working (and pretty much complete) specimen. This is one of the
later models: half-height floppy drive + ST-225 hard drive, 640K
motherboard (fully populated), last BIOS revision (05/86). The latest
date code on the chips is 8649, so this machine was made shortly before
the XT was discontinued altogether.

I received this from Trixter, truly a
gentleman and a scholar, along with a separate box of stuff to round it
out: an IBM PC/XT keyboard, a joystick, some software/games (including a
boxed IBM PC-DOS 3.30), and the Guide to Operations. The machine itself
is very well-equipped too, complete with an XT-CF adapter, an IBM CGA
board, and a Sound Blaster Pro 2.0, but more about that in a bit.

This thing went through a bit of a misadventure en-route to me. USPS
turned out to have some inexplicable restrictions on package sizes to my
country - except for Global Priority Express shipments... and I don't
need to tell you how much that would've cost. The only available box
that satisfied these arbitrary limits didn't leave much room for extra
protective padding on the sides. After some consideration, we decided to
brave it anyway: those early IBMs are built like brick shithouses and
could stand being knocked around a bit, right? So, off it went on its
merry way with as much compressed foam as could be stuffed around the
sides and corners.

My first clue that something was wrong came when I picked up the package
from the post office, and heard the ominous yet unmistakable sounds of
something rattling inside... uh oh. Opening it up, it was immediately
evident that we had underestimated our respective postal services'
capacity for malicious damage.

XT unboxing horror! (click for full size)

In case these photos do not convey the full magnitude of the crime:
something, somehow, has managed to apply such a massive amount of force
to this box that the corners of the cover were savagely bent inwards at
the back, on both sides. Remember, we're talking heavy-gauge sheet
metal. This initially prevented me from even removing the cover at all,
until I employed a screwdriver and a hammer rather forcefully (the
thought still makes me wince a little).

The cover yielded, and it transpired that the rattling I'd heard was
only the PC speaker, which had been knocked out of its holder; that was
the least of my problems. The back panel (also metal) evidently got a
vicious whack on its right side, just where the card brackets go. This
shoved everything forward, also slamming the full-length CGA board
against the front of the case and dislodging the little plastic brace
that keeps it in place there. The hard drive bay cover wasn't spared
either; one of the lobes where it's screwed to the chassis was broken
off.

Surveying the innards (click for full size)

None of the important components appeared to be busted or injured, but
this naturally left me a bit dispirited, fearing damage to the cards,
the slots and/or the motherboard... let alone the bits I couldn't
inspect at a glance, like the mechanical innards of the floppy drive.
However, testing was gonna have to wait, since I was going away for a
couple of weeks and didn't yet have a 220V to 110V step-down transformer
(the PSU is American).

Imagine my considerable delight when I came back, got the power
converter, plugged everything in, and gingery flipped the Big Red
Switch... then the RAM test crawled its way up the count, to finally greet
me with this heart-warming display:

PHEW

Rock 'n' roll! Yep, it Just Worked. Actually, everything just worked;
the CF card was helpfully packed with diagnostic programs,
music/graphics stuff and so on, so I soon established that there were no
casualties except the aesthetics: from the sound card to the floppy
drive, all systems are go.

See, those early IBMs were sturdy steel beasts and for that I am
thankful. I'm not sure how they managed to inflict such next level
punishment on the package, but they must've tried real hard to brutalize
it like that. If this was any kind of plastic-cased computer (or
monitor), I'd be fishing jigsaw puzzle pieces out of that box. But even
with a few nicks in its armor, the IBM XT is a die-hard heavy metal road
warrior.

Now that things were looking good, I took out the cards, applied more
physical persuasion where needed, and soon the case and cover were
looking much better:

Rear shot after some gentle care (click for full size)

So, what's inside?

IBM CGA (later revision, with the 'new-style' composite output)

IBM Diskette Drive Adapter (later revision, Intel P8272A FDC chip)

XT-CF-Lite v4.1 board (prototype based on Sergey Malinov's redesign)

Sound Blaster Pro 2.0 (CT1600)

Serial/Parallel board

RTC board (with a button-cell CR2032 battery)

Half-height 5.25" DSDD floppy drive

20MB Seagate ST-225 hard drive (this came with the system, but it's
unplugged as I'm using the CF card; I do have the controller for it
though).

My modern LCD TV plays nice enough with CGA signals over composite, but
that's not terribly convenient (nor 'authentic') so I looked around for
something else. By a lucky coincidence, a TV repair shop literally down
the street from me had a nice CRT TV for cheap - a 1999 Brother set with
a TINT control, which confirmed NTSC compatibility (something you can't
take for granted in this PAL country). The 14" size makes it a neat
substitute for a monitor.(click for full size)

Being composite, of course it isn't ideally suited for 80-column text
mode in color. It can be made to work, but there's a reason why it's
always been considered pretty much unreadable:

80-column CGA text on TV (click for full size)

The keyboard is in excellent shape. People talk a lot of smack about the
original PC/XT layout, and it's far from ideal, but I'm not finding it
that difficult to adapt. After all, the first keyboard I ever typed on
was like that. And the capacitive buckling spring keys are like a party
under your fingers! [Read as an overexcited Rajesh from Big Bang
Theory]

The CF card has single DOS 6.22 partition. True, 6.22 is a memory hog
when you can't throw HMA or UMBs at it; and the first DIR after a reboot
can take some 20 seconds to calculate the free space... but the 2GB of
space are worth it, and so is the speed:

CheckIt v3.0 benchmarks w/XT-CF card (click for full size)

For games, there's the Total DOS
Launcher which
Trixter has been working on. Not really final yet, but it works great;
this is a game organizer/launcher which doesn't need any per-game
configuration, lets you store your games in ZIPs, index them by running
a script (on a modern system) and just copy them over and play. Runs on
just about anything, from an 8088 (even a PCjr) and up. With a newer
system you can use fancy VESA text modes too; but since I'm displaying
CGA on a TV, I either run it in 40 columns (if I want color) or 80
columns in B&W.

Total DOS launcher in action! (click for full size)

Running some more cool stuff just for the heck of it:

Commander Keen 5 - composite CGA patch (click for full size)8088 MPH (click for full size)Leisure Suit Larry I (click for full size)Below the Root (click for full size)

Going through these old games again on the original hardware, it's
sometimes remarkable to find what sticks with you even after decades.
When I was about 9 I used to play the shit out of Cosmic Crusader, and I
got real good at it. You know how when you kick ass at a game, you
develop an almost instinctual muscle-memory for playing it? After all
these years it's apparently still there, and I can get "in the zone"
with very little effort. Funny how that works.

And of course: an IBM 5153 monitor. I really don't know how I'd get
one shipped, though... there's no way it could survive the extreme
abuse that the XT did, and I've seen enough horror stories of such
monitors arriving in way more than one piece.

2 comments:

Great Post / Great Project - Reminds me of the 8088 I first used in business with 9600 baud modem we actually used for our fax machine in addition to accounting (WriteOne) and word processing (BetterWorkingWordPublisher.) it was DOS v4.0 though

My first personal computer was IBM 286 running DOS 5.5, PGA graphics with 1MB memory expansion, 20MB MFM stacked to 40... I was running that while the rest of the world was running 486's and doing more with it than many thought possible.

I miss those days for a great many reasons and appreciate this website for all the right ones :D

PGA graphics! That's quite a thing to have on a first PC. There's recently been some interest in emulating the PGA, wonder what will come of it.

And this is my first true-blue IBM machine ever - all I ever had were clones, starting from a turbo XT which was a nameless Taiwanese job... probably won't ever find out what model it was, but then they were all pretty interchangeable.